From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f47.google.com (mail-pa0-f47.google.com [209.85.220.47]) by kanga.kvack.org (Postfix) with ESMTP id 1BBE66B006C for ; Thu, 29 Jan 2015 18:13:34 -0500 (EST) Received: by mail-pa0-f47.google.com with SMTP id lj1so44309677pab.6 for ; Thu, 29 Jan 2015 15:13:33 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id x10si11730522pdk.16.2015.01.29.15.13.33 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Jan 2015 15:13:33 -0800 (PST) Date: Thu, 29 Jan 2015 15:13:32 -0800 From: Andrew Morton Subject: Re: [PATCH v10 17/17] kasan: enable instrumentation of global variables Message-Id: <20150129151332.3f87c0b2e335afd88af33e08@linux-foundation.org> In-Reply-To: <1422544321-24232-18-git-send-email-a.ryabinin@samsung.com> References: <1404905415-9046-1-git-send-email-a.ryabinin@samsung.com> <1422544321-24232-1-git-send-email-a.ryabinin@samsung.com> <1422544321-24232-18-git-send-email-a.ryabinin@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin Cc: linux-kernel@vger.kernel.org, Dmitry Vyukov , Konstantin Serebryany , Dmitry Chernenkov , Andrey Konovalov , Yuri Gribov , Konstantin Khlebnikov , Sasha Levin , Christoph Lameter , Joonsoo Kim , Dave Hansen , Andi Kleen , x86@kernel.org, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Rusty Russell , Michal Marek , "open list:KERNEL BUILD + fi..." On Thu, 29 Jan 2015 18:12:01 +0300 Andrey Ryabinin wrote: > This feature let us to detect accesses out of bounds > of global variables. global variables *within modules*, I think? More specificity needed here. > The idea of this is simple. Compiler increases each global variable > by redzone size and add constructors invoking __asan_register_globals() > function. Information about global variable (address, size, > size with redzone ...) passed to __asan_register_globals() so we could > poison variable's redzone. > > This patch also forces module_alloc() to return 8*PAGE_SIZE aligned > address making shadow memory handling ( kasan_module_alloc()/kasan_module_free() ) > more simple. Such alignment guarantees that each shadow page backing > modules address space correspond to only one module_alloc() allocation. > > ... > > +int kasan_module_alloc(void *addr, size_t size) > +{ > + > + size_t shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT, > + PAGE_SIZE); > + unsigned long shadow_start = kasan_mem_to_shadow((unsigned long)addr); > + void *ret; Like this: size_t shadow_size; unsigned long shadow_start; void *ret; shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT, PAGE_SIZE); shadow_start = kasan_mem_to_shadow((unsigned long)addr); it's much easier to read and avoids the 80-column trickery. I do suspect that void *kasan_mem_to_shadow(const void *addr); would clean up lots and lots of code. > + if (WARN_ON(!PAGE_ALIGNED(shadow_start))) > + return -EINVAL; > + > + ret = __vmalloc_node_range(shadow_size, 1, shadow_start, > + shadow_start + shadow_size, > + GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, > + PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE, > + __builtin_return_address(0)); > + return ret ? 0 : -ENOMEM; > +} > + > > ... > > +struct kasan_global { > + const void *beg; /* Address of the beginning of the global variable. */ > + size_t size; /* Size of the global variable. */ > + size_t size_with_redzone; /* Size of the variable + size of the red zone. 32 bytes aligned */ > + const void *name; > + const void *module_name; /* Name of the module where the global variable is declared. */ > + unsigned long has_dynamic_init; /* This needed for C++ */ This can be removed? > +#if KASAN_ABI_VERSION >= 4 > + struct kasan_source_location *location; > +#endif > +}; > > ... > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org